WASHINGTON — The US Justice Department on Thursday announced an investigation into policing in Phoenix, Arizona focused on overuse of force, discrimination and abuse of homeless people and those with mental health issues.

It is the third “pattern and practice” investigation into the police of a major US city launched by Attorney General Merrick Garland, in the wake of last year’s national uproar over the high number of African Americans killed by law enforcement.

“This investigation will assess all types of use of force by PhxPD officers, including deadly force,” the Justice Department said in a statement, referring to the Phoenix Police Department.

The investigation will examine whether police in the sprawling southwestern city systematically abuse their powers, violating civil rights.

According to Phoenix media, of the last several years, the rate of police use of force was higher in the city than most other major urban areas.

In addition, Black Americans were the subjects of a high number of use-of-force incidents.

“Pattern and practice” investigations can lead to the Justice Department and the city reaching a consent decree that legally requires the locality to implement specific reforms on a clear timeline.

If a consent decree is not reached, the Justice Department can take the city or its police department to court.

“These investigations aim to promote transparency, and accountability,” Garland said.

He said the city police chief and mayor had welcomed the probe.

In April, Garland launched similar investigations into the police in Louisville, Kentucky and Minneapolis, Minnesota, where law enforcement had recently killed African-American residents without justification and tried to cover up the circumstances of the incidents.

Garland also said one of the focuses of the Phoenix probe is on police treatment of people with mental and social problems.

He said the Covid-19 pandemic and ensuing economic downturn had worsened the situations of people with mental health problems, as well as contributed to homelessness.

Homelessness could rise in the coming months, he warned, after the expiration of a moratorium on evictions.

“Our society is straining the policing profession by turning to law enforcement  to address a wide array of social problems,” he said.

Police are often the first to be called to deal with a homeless person having a mental health crisis, he noted.

“The risks to everyone involved in such interactions are enormous,” he said.

Homelessness “strains but cannot be solved by the criminal justice system,” Garland said.